fuel psi. for 24lb. injectors??

12-18-2003, 08:28 PM

I run 24lb. injectors with my Edel. H/C/I combination. Yes, my MAM is calibrated for the 24s. My question is what fuel pressure should I be running? I used to run around 38psi. w/ the vacuum hose connected to the FPR...which is the stock setting pretty much. I'm pulling codes 41 & 91 which says the O2s are at their lean limit. I've been told that they are trying to lean out my rich air/fuel mixture, but are at their leaning limits. I do have an adjustable FPR...so where do you think I should be at? Maybe 32psi.? What will happen if I turn it down too low? Besides tripping up a trouble code...will I know by the sound of the motor or anything? Because I can't imagine my plugs (which look perfect right now) becoming completely white all of a sudden if it was running lean. What are you guys with 24lb. injectors and aftermarket H/C/I running your fuel psi. at?

420nitro · 12-18-2003, 08:44 PM

I had a similar set-up and ran 36 psi with the vacuum hose disconnected at the fpr...and had great results.
I also had a friend which had is pro-m mas air meter calibrated wrong which caused havoc! The meter was so-called calibrated for the injectors he was running too. Wasn't untill he sent his maf.. in before he knew it was messed up.
Which meter are you running?

12-18-2003, 08:58 PM

Quote:

Originally posted by 420nitro
Which meter are you running?

Thanks for the reply 420nitro. I'm running a Vortech 73mm MAM calibrated for my 24lb. injectors. What H/C/I combination were you running when you ran 36psi. w/ vacuum disconnected?

How about you other guys with 24lb. injectors and aftermarket H/C/I...what's your fuel psi. at?? Just want to get multiple opinions on this.

JSFIRE79 · 12-18-2003, 09:07 PM

Im still running 38Psi And it runs great.....I also run the 24Lbs injectors , as well as a 255 pump, on the 125 shot.....I've also ran it at 32lbs. And my plugs looked great.......never had any prblems....trying to play with it though.......your plugs are whats really gonna tell how lean/rich you are. I'd say they are the more acurate source.

mustangman4 · 12-19-2003, 03:21 AM

As far as fuel pressure goes 38-40lbs should be sufficient as long as the fuel pump can keep up. In your situation you should be fine. As far as the 02 sensor codes go lean is dangerous. You will eventually start hurting the motor when you go too low. More fuel can never hurt. You may foul a plug or two but thats it. Try running it up to 42-43 then check plugs. The only way to really check them is doing a WOT pass in 3rd or 4th gear. Then check them. You will pick up ponies as you start to lean it out but when the ECU figures out that you did it it will try to richen it up again. It likes to maintain a proper A/F ratio throughout the RPM range. More fuel pressure makes the injectors think they are larger than they really are. Thats where the whole adj fuel pressure regulator idea really came about. With the proper inj mass air combo you should never really need to go past 45lbs on a N/A combo. Hope this helps.

Brad

exgmguy · 12-19-2003, 03:04 PM

38 psi without vacuum. The computer will make it's own adjustments.

12-18-2003, 08:28 PM	#1
Simi Stang Guest Posts: n/a	fuel psi. for 24lb. injectors?? I run 24lb. injectors with my Edel. H/C/I combination. Yes, my MAM is calibrated for the 24s. My question is what fuel pressure should I be running? I used to run around 38psi. w/ the vacuum hose connected to the FPR...which is the stock setting pretty much. I'm pulling codes 41 & 91 which says the O2s are at their lean limit. I've been told that they are trying to lean out my rich air/fuel mixture, but are at their leaning limits. I do have an adjustable FPR...so where do you think I should be at? Maybe 32psi.? What will happen if I turn it down too low? Besides tripping up a trouble code...will I know by the sound of the motor or anything? Because I can't imagine my plugs (which look perfect right now) becoming completely white all of a sudden if it was running lean. What are you guys with 24lb. injectors and aftermarket H/C/I running your fuel psi. at?

12-18-2003, 09:07 PM	#4
JSFIRE79 Registered Member Join Date: Sep 2000 Location: Northridge, Ca. USA Posts: 27	Im still running 38Psi And it runs great.....I also run the 24Lbs injectors , as well as a 255 pump, on the 125 shot.....I've also ran it at 32lbs. And my plugs looked great.......never had any prblems....trying to play with it though.......your plugs are whats really gonna tell how lean/rich you are. I'd say they are the more acurate source. __________________ 93GT Stock 302, 170,000 miles....GT-40Y Heads, Ported and Extrude Honed GT-40 intake, Pro-M w/Granitelli Meter , 65mm Throttle Body , Custom Crane Cam, Rockers, lifters, pushrods, Mikes Transmissions Built AOD, 3000 stall, Aluminum Driveshaft , 3.73 gears, Motorsports shorty headers, Stock axles, ZEX 125HP kit. w/Bottle warmer. 60ft. - 1.60 1/4- 11.38 MPH- 119 WWW.StarkRacing.net

12-19-2003, 03:21 AM	#5
mustangman4 Registered Member Join Date: Feb 2003 Location: Oshkosh WI Posts: 69	As far as fuel pressure goes 38-40lbs should be sufficient as long as the fuel pump can keep up. In your situation you should be fine. As far as the 02 sensor codes go lean is dangerous. You will eventually start hurting the motor when you go too low. More fuel can never hurt. You may foul a plug or two but thats it. Try running it up to 42-43 then check plugs. The only way to really check them is doing a WOT pass in 3rd or 4th gear. Then check them. You will pick up ponies as you start to lean it out but when the ECU figures out that you did it it will try to richen it up again. It likes to maintain a proper A/F ratio throughout the RPM range. More fuel pressure makes the injectors think they are larger than they really are. Thats where the whole adj fuel pressure regulator idea really came about. With the proper inj mass air combo you should never really need to go past 45lbs on a N/A combo. Hope this helps. Brad __________________ 93 GT 306 DSS, O-Ringed, AFR 185's, Pro Products Intakes, 55lb low imp inj, 80mm Pro-M meter, 2004 PMS, AFM Power Pipe, Kirban Reg, Vortech S-Trim 14lbs. No times yet. Trying to tune.

12-19-2003, 03:04 PM	#6
exgmguy Registered Member Join Date: Feb 1999 Location: Utica, Michigan Posts: 2,631	38 psi without vacuum. The computer will make it's own adjustments. __________________ 1988 Mustang GT stock bottom 302, C4 10.9 @ 128 with 8 psi of Novi 1000 boost!----STOLEN 1989 Mustang notchback Warmed up 306 with a Procharger.

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12-18-2003, 08:44 PM	#2
420nitro Registered Member Join Date: Nov 2003 Location: Rockford Posts: 596	I had a similar set-up and ran 36 psi with the vacuum hose disconnected at the fpr...and had great results. I also had a friend which had is pro-m mas air meter calibrated wrong which caused havoc! The meter was so-called calibrated for the injectors he was running too. Wasn't untill he sent his maf.. in before he knew it was messed up. Which meter are you running?